The present disclosure relates to an embroidery data creation apparatus and a computer-readable recording medium storing an embroidery data creation program. More specifically, the present disclosure relates to an embroidery data creation apparatus and a computer-readable recording medium storing an embroidery data creation program both of which are capable of adjusting a stitching direction when performing embroidery sewing based on a photographic image.
Conventionally, embroidery sewing may be performed based on an image of a photograph taken with a digital camera or of a photograph printed from a film. In such an example, image data of a photograph taken with a digital camera or image data obtained by scanning a photograph printed from a film with a scanner may be used. From the image data, line segment data and color data may be created. The line segment data indicates a shape of a stitch of a thread to be used for embroidery sewing, while the color data indicates a color of the stitch. Then, from the line segment data and the color data, embroidery data that indicates stitches for each thread color is created. For example, Japanese Patent Application Laid-Open Publication No. 2001-259268 discloses an embroidery data creation apparatus. The apparatus creates the embroidery data based on the line segment data that indicates the shape of a stitch so that stitches are aligned in not only one direction but also with a variety of directional angles within 360°, in order to make an embroidery result look closer to the image of the photograph. Specifically, for each of the pixels that constitute the image data, the apparatus calculates a stitching direction (angle characteristic) and its intensity (angle characteristic intensity) based on a relationship to its surrounding pixels, and uses the angle characteristic and angle characteristic intensity when creating the line segment data. The angle characteristic and the angle characteristic intensity are calculated based on luminance of a target pixel and luminance of surrounding pixels of the target pixel. The greater the difference between the luminance of the target pixel and the luminance of the surrounding pixels, the greater the value of the angle characteristic intensity becomes.
Further, for example, Japanese Patent Application Laid-Open Publication No. Hei 5-146574 discloses a data processing apparatus for embroidery sewing machines. The apparatus permits a user to specify a stitching direction in the embroidery data. In the data processing apparatus, the stitching direction is determined based on points that are specified on a borderline of an embroidery region in which embroidery sewing is to be performed. Furthermore, for example, Japanese Patent Application Laid-Open Publication No. Hei 11-19351 discloses a method for setting a stitching direction. According to this stitching direction setting method, the stitching direction in an embroidery region is specified by moving a mouse cursor over an embroidery region in which embroidery sewing is to be performed.
However, the above-described conventional embroidery data creation apparatus may in some examples create a stitch in an undesirable direction. For example, an original photographic image 90 of a design to be embroidered shown in FIG. 26 contains a background and a face of a girl wearing a cap, in which there is little difference in luminance in the background. FIG. 27 shows line segment data created based on the angle characteristics and angle characteristic intensities that are calculated from the photographic image shown in FIG. 26. Line segments of FIG. 27 indicate the shape of the stitches. Embroidery data can be created by assigning a color to each of those line segments. The background of the photographic image 90 may look more distinct in indicating the same area and may be more beautiful when the entire background is embroidered in the same stitching direction. In a region 911 shown in FIG. 27 corresponding to a region 91 shown in FIG. 26, the line segments in the left half of the region 911 that are close to the left end of the photographic image 90 are aligned in almost the same direction. On the other hand, the line segments in the right half of the region 911 that are close to the borderline with the cap are aligned in various directions. Because there is little difference in the luminance within the region 911, the created line segments tend to be aligned in the same direction, if the luminance is used to calculate the angle characteristics and the angle characteristic intensities. However, in the vicinity of the borderline between the background and the cap, the calculated values of the angle characteristics and the angle characteristic intensities are affected by the luminance of the cap, so that the created line segments are aligned in the different directions.
Further, a photographic image 80 shown in FIG. 28 contains a face of a male. For sewing embroidery based on the photographic image 80, a hair portion 81 may look more natural and beautiful if stitches are formed along an actual flow of the hair. However, the hair portion 81 in the photographic image 80 looks like the portion is painted all black. Therefore, if an embroidery data is created from such a photographic image 80, created line segments at the center of the hair portion 81 will be aligned in almost the same direction.
Moreover, according to the conventional data processing apparatuses and the conventional stitching direction setting methods, all stitching directions in a region are specified. Therefore, those conventional apparatuses and methods may not always be suitable for embroidery sewing based on a photographic image, in this example the sewing result can be made to look closer to the photographic image by forming stitches that have a variety of directional angles within 360° and fit in well with stitching directions and colors of the surrounding stitches.